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C40R

1.1189
Carbon SteelUnalloyed
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Unalloyed special steel with controlled sulfur (R grade, S 0.020–0.040%) and 0.40% carbon for improved machinability. Same base composition as C40E but with intentional sulfur for better chip formation in automated machining. Used for shafts, bolts, gears, and general machine parts requiring good strength with high production rates.

Chemical composition comparison (wt%)

Side-by-side: C40R (EN) (EN 10083-2:2006) vs ASTM

ElementC40R (EN)ASTMOverlap
C0.37–0.44%——
Si≤ 0.4%——
Mn0.5–0.8%——
P≤ 0.025%——
S0.02–0.04%——

Mechanical properties

Normalized

PropertyValueUnit
Tensile Strength580–730MPa
Yield Strength≥ 320MPa
Elongation≥ 16%
Hardness HB175–215HB
Density≥ 7.85g/cm3
Elastic Modulus≥ 210GPa

Heat treatment

ProcessTemperatureMediumHolding TimeNotes
normalizing850–880 °Cair——
quenching820–860 °Coil—Water possible for small sections
tempering550–660 °Cair——
annealing650–700 °Cfurnace—Soft annealing max 207 HB

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All data is for reference only. Equivalents indicate similarity, not identity. Always verify against the applicable specification for safety-critical applications. materialref.com accepts no liability for decisions based on this data.